1. Technical Field
The present invention relates to mine drainage immobilization, and more particularly to an apparatus and in-situ method for immobilizing water collected within spent and/or abandoned mine works.
2. Description Of Related Art
It is a well known phenomenon that water can and does collect within underground mines. As this water collects, it has a tendency to leach the soluble compounds within the adjacent ground and/or ore body. For example, many of the copper and lead mines in California are formed through an ore body which is high in sulfides. As such, the sulfides have a tendency to leach out of the adjacent ground and into the water collecting within the mine workings, thereby generating a highly acidic mine drainage. This highly acidic mine drainage, in turn, has a tendency to dissolve the residual metals, such as copper and lead, into the mine drainage. Because such mine water is highly acidic and contains a relatively high concentration of metal, there is a high potential for pollution of adjacent streams, rivers and lakes resulting from the discharge thereof.
Mine drainage is recognized as a potential environmental concern attracting the attention of both industry and government in the United States and throughout the world. Many processes have been proposed for purifying such acid mine drainage after it is discharged from the mine, but before it is allowed to enter the nearby waterways. Normally, these processes require that the water discharged from the underground mine be collected on the surface in large retention ponds at which point additives are injected into the retained waters in attempt to neutralize this drainage. For example, highly acidic mine drainage will be injected with a suitable alkaline materials to raise the pH factor to a near neutral state. Once the mine drainage has been neutralized, it is transported to a secondary settling pool where the metals and other pollutants are allowed to precipitate out of the water. Only after these steps is the treated water considered suitable for discharge into the environment.
This procedure has recognized deficiencies. For example, over a period of time, the retention pond and settling pool have a tendency to fill with the precipitated minerals and other material, thereby requiring removal thereof. However, due to the chemical makeup of these precipitants, specialized handling and disposal is often required. As such, the prior art methods of treating acid mine drainage often requires a large amount of surface area adjacent to the underground mine which is suitable for forming the retention ponds and settling pools. In addition, while some mine sites lend themselves to these requirements, many of the mine sites, particularly in very mountainous terrain, do not have the requisite surface area available. Furthermore, heavy industrial equipment is required at such sites many of which are remote with no electricity or other infrastructure available for building these facilities, as well as removal and disposal of the precipitated wastes.